Monday, November 16, 2009

When Charles Darwin visited the Falkland Islands during the voyage of the Beagle in 1835, he saw a wolf-like species, wrote about it in his diaries and correctly commented that it was being hunted in such large numbers that it would soon become extinct. Darwin was baffled by how this animal got on the islands, and it figured heavily in the formation of his ideas on evolution by natural selection.

The wolf was the only terrestrial mammal on the island, but was it brought to the Falklands, less than 300 miles from the mainland of South America, by humans or did it somehow get there by itself?

Scientists have analyzed DNA samples from five Falkland Islands wolves and calculated how long ago those five wolves shared a common ancestor.

"It was at least 70,000 years ago — well before humans came to the New World," Slater said.

"The Falkland Islands wolf clearly precedes any possible human occupation of the New World, which dates back some 12,000 to 13,000 years."

Darwin hypothesized that the Falkland Islands wolf, which became extinct in 1876, may have come to the islands on icebergs. Wayne and Slater think Darwin may be right.

"A large, wolf-size animal could perhaps live on a large iceberg with penguins and sea birds and maybe seals — enough prey to survive the voyage.

The closest relative to the Falkland Islands wolf, the biologists report, is an odd South American dog species called the maned wolf, which looks nothing like the Falklands species.

"The closet living relative of the maned wolf is the bush dog, which is even more different," Slater said. "These three are a strange group."link

Saturday, November 7, 2009

A new study shows that animal communities on the abyssal seafloor are affected in a variety of ways by climate change, some changes occurring within a few weeks.

Available food there is takes the form of bits of organic debris drifting down from the sunlit surface waters, thousands of meters above. It is estimated that less than five percent of the organic matter produced at the surface reaches the abyssal plains. Research shows that the amount of food reaching the deep sea varies dramatically over time.

Click to enlarge & read

Some relevant ocean processes that may be affected by climate change include wind-driven upwelling, the depth of mixing of the surface waters, and the delivery of nutrients to surface waters via dust storms. Climate-driven changes in these processes are likely to lead to altered year-to-year variation in the amount of organic material reaching the seafloor. link